Atmosphere
An atmosphere (from Greek ἀτμός (atmos), meaning 'vapour', and
σφαῖρα (sphaira), meaning 'sphere'[1][2]) is a layer or a set
of layers of gases surrounding a planet or other material body, that
is held in place by the gravity of that body. An atmosphere is more
likely to be retained if the gravity it is subject to is high and the
temperature of the atmosphere is low.
The atmosphere of
EarthEarth is composed of nitrogen (about 78%), oxygen
(about 21%), argon (about 0.9%) with carbon dioxide and other gases in
trace amounts.
OxygenOxygen is used by most organisms for respiration;
nitrogen is fixed by bacteria and lightning to produce ammonia used in
the construction of nucleotides and amino acids; and carbon dioxide is
used by plants, algae and cyanobacteria for photosynthesis. The
atmosphere helps to protect living organisms from genetic damage by
solar ultraviolet radiation, solar wind and cosmic rays
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Radiation
In physics, radiation is the emission or transmission of energy in the
form of waves or particles through space or through a material
medium.[1][2] This includes:electromagnetic radiation, such as radio waves, microwaves, visible
light, x-rays, and gamma radiation (γ)
particle radiation, such as alpha radiation (α), beta radiation (β),
and neutron radiation (particles of non-zero rest energy)
acoustic radiation, such as ultrasound, sound, and seismic waves
(dependent on a physical transmission medium)
gravitational radiation, radiation that takes the form of
gravitational waves, or ripples in the curvature of spacetime.
RadiationRadiation is often categorized as either ionizing or non-ionizing
depending on the energy of the radiated particles. Ionizing radiation
carries more than 10 eV, which is enough to ionize atoms and
molecules, and break chemical bonds. This is an important distinction
due to the large difference in harmfulness to living organisms
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E (mathematical Constant)
The number e is a mathematical constant, approximately equal to
2.71828, which appears in many different settings throughout
mathematics. It was discovered by the Swiss mathematician Jacob
Bernoulli while studying compound interest,[1] where e arises as the
limit of (1 + 1/n)n as n approaches infinity
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Force
In physics, a force is any interaction that, when unopposed, will
change the motion of an object.[1] A force can cause an object with
mass to change its velocity (which includes to begin moving from a
state of rest), i.e., to accelerate.
ForceForce can also be described
intuitively as a push or a pull. A force has both magnitude and
direction, making it a vector quantity. It is measured in the SI unit
of newtons and represented by the symbol F.
The original form of
Newton's second lawNewton's second law states that the net force
acting upon an object is equal to the rate at which its momentum
changes with time
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Modification Detection Code
A cryptographic hash function is a special class of hash function that
has certain properties which make it suitable for use in cryptography.
It is a mathematical algorithm that maps data of arbitrary size to a
bit string of a fixed size (a hash) and is designed to be a one-way
function, that is, a function which is infeasible to invert. The only
way to recreate the input data from an ideal cryptographic hash
function's output is to attempt a brute-force search of possible
inputs to see if they produce a match, or use a rainbow table of
matched hashes
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Weight
In science and engineering, the weight of an object is related to the
amount of force acting on the object, either due to gravity or to a
reaction force that holds it in place.[1][2][3]
Some standard textbooks[4] define weight as a vector quantity, the
gravitational force acting on the object. Others[5][6] define weight
as a scalar quantity, the magnitude of the gravitational force.
Others[7] define it as the magnitude of the reaction force exerted on
a body by mechanisms that keep it in place: the weight is the quantity
that is measured by, for example, a spring scale. Thus, in a state of
free fall, the weight would be zero
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UltravioletUltravioletUltraviolet (UV) is an electromagnetic radiation with a wavelength
from 100 nm to 400 nm, shorter than that of visible light
but longer than X-rays. UV radiation is present in sunlight
constituting about 10% of the total light output of the Sun. It is
also produced by electric arcs and specialized lights, such as
mercury-vapor lamps, tanning lamps, and black lights. Although
long-wavelength ultraviolet is not considered an ionizing radiation
because its photons lack the energy to ionize atoms, it can cause
chemical reactions and causes many substances to glow or fluoresce.
Consequently, the chemical and biological effects of UV are greater
than simple heating effects, and many practical applications of UV
radiation derive from its interactions with organic molecules.
Suntan and sunburn are familiar effects of over-exposure of the skin
to UV, along with higher risk of skin cancer
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PhotosynthesisPhotosynthesisPhotosynthesis is a process used by plants and other organisms to
convert light energy into chemical energy that can later be released
to fuel the organisms' activities (energy transformation). This
chemical energy is stored in carbohydrate molecules, such as sugars,
which are synthesized from carbon dioxide and water – hence the name
photosynthesis, from the Greek φῶς, phōs, "light", and
σύνθεσις, synthesis, "putting together".[1][2][3] In most
cases, oxygen is also released as a waste product. Most plants, most
algae, and cyanobacteria perform photosynthesis; such organisms are
called photoautotrophs
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Cyanobacteria
As of 2014[update] the taxonomy was under revision[1][2]Chroococcales
Chroococcidiopsidales
Gloeobacterales
Nostocales
Oscillatoriales
Pleurocapsales
Spirulinales
Synechococcales
Incertae sedis†Gunflintia†OzarkcolleniaSynonymsMyxophyceae Wallroth, 1833
Phycochromaceae Rabenhorst, 1865
Cyanophyceae Sachs, 1874
Schizophyceae Cohn, 1879
Cyanophyta Steinecke, 1931
Oxyphotobacteria Gibbons & Murray, 1978
CyanobacteriaCyanobacteria /saɪˌænoʊbækˈtɪəriə/, also known as Cyanophyta,
are a phylum of bacteria that obtain their energy through
photosynthesis,[4] and are the only photosynthetic prokaryotes able to
produce oxygen.[5] The name "cyanobacteria" comes from the color of
the bacteria (Greek: κυανός, translit. kyanós,
lit. 'blue').[6][7]
CyanobacteriaCyanobacteria (which are prokaryotes) used to
be called "blue-green algae"
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AlgaeAlgaeAlgae (/ˈældʒi, ˈælɡi/; singular alga /ˈælɡə/) is an
informal term for a large, diverse group of photosynthetic organisms
that are not necessarily closely related, and is thus polyphyletic.
Included organisms range from unicellular microalgae genera, such as
ChlorellaChlorella and the diatoms, to multicellular forms, such as the giant
kelp, a large brown alga which may grow up to 50 m in length.
Most are aquatic and autotrophic and lack many of the distinct cell
and tissue types, such as stomata, xylem, and phloem, which are found
in land plants. The largest and most complex marine algae are called
seaweeds, while the most complex freshwater forms are the Charophyta,
a division of green algae which includes, for example,
SpirogyraSpirogyra and
the stoneworts.
No definition of algae is generally accepted
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Barometer
A barometer is a scientific instrument used in meteorology to measure
atmospheric pressure.
PressurePressure tendency can forecast short term
changes in the weather. Numerous measurements of air pressure are used
within surface weather analysis to help find surface troughs, high
pressure systems and frontal boundaries.
Barometers and pressure altimeters (the most basic and common type of
altimeter) are essentially the same instrument, but used for different
purposes. An altimeter is intended to be transported from place to
place matching the atmospheric pressure to the corresponding altitude,
while a barometer is kept stationary and measures subtle pressure
changes caused by weather
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Amino AcidsAmino acidsAmino acids are organic compounds containing amine (-NH2) and carboxyl
(-COOH) functional groups, along with a side chain (R group) specific
to each amino acid.[1][2][3] The key elements of an amino acid are
carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), although other
elements are found in the side chains of certain amino acids. About
500 naturally occurring amino acids are known (though only 20 appear
in the genetic code) and can be classified in many ways.[4] They can
be classified according to the core structural functional groups'
locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-)
amino acids; other categories relate to polarity, pH level, and side
chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or
sulfur, etc.)
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Molecule
A molecule is an electrically neutral group of two or more atoms held
together by chemical bonds.[4][5][6][7][8] Molecules are distinguished
from ions by their lack of electrical charge. However, in quantum
physics, organic chemistry, and biochemistry, the term molecule is
often used less strictly, also being applied to polyatomic ions.
In the kinetic theory of gases, the term molecule is often used for
any gaseous particle regardless of its composition. According to this
definition, noble gas atoms are considered molecules as they are
monoatomic molecules.[9]
A molecule may be homonuclear, that is, it consists of atoms of one
chemical element, as with oxygen (O2); or it may be heteronuclear, a
chemical compound composed of more than one element, as with water
(H2O)
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Nucleotides
Nucleotides are organic molecules that serve as the monomer units for
forming the nucleic acid polymers deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA), both of which are essential biomolecules in
all life-forms on Earth. Nucleotides are the building blocks of
nucleic acids; they are composed of three subunit molecules: a
nitrogenous base, a five-carbon sugar (ribose or deoxyribose), and at
least one phosphate group. They are also known as phosphate
nucleotides.
A nucleoside is a nitrogenous base and a 5-carbon sugar. Thus a
nucleoside plus a phosphate group yields a nucleotide.
Nucleotides also play a central role in life-form metabolism at the
fundamental, cellular level
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Nitrogen FixationNitrogenNitrogen fixation is a process by which nitrogen in the Earth's
atmosphere is converted into ammonia (NH3) or other molecules
available to living organisms.[1] Atmospheric nitrogen or molecular
dinitrogen (N2) is relatively inert: it does not easily react with
other chemicals to form new compounds. The fixation process frees
nitrogen atoms from their triply bonded diatomic form, N≡N, to be
used in other ways.
NitrogenNitrogen fixation is essential for some forms of life because
inorganic nitrogen compounds are required for the biosynthesis of the
basic building blocks of plants, animals and other life forms, e.g.,
nucleotides for DNA and RNA, the coenzyme nicotinamide adenine
dinucleotide for its role in metabolism (transferring electrons
between molecules), and amino acids for proteins. Therefore, as part
of the nitrogen cycle, it is essential for agriculture and the
manufacture of fertilizer
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Surface Gravity
The surface gravity, g, of an astronomical or other object is the
gravitational acceleration experienced at its surface. The surface
gravity may be thought of as the acceleration due to gravity
experienced by a hypothetical test particle which is very close to the
object's surface and which, in order not to disturb the system, has
negligible mass.
Surface gravity is measured in units of acceleration, which, in the SI
system, are meters per second squared
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